No player over the two legs of this tie will get as much attention as Ronaldo. His 182 goals in 179 games at Real Madrid is a phenomenal stat compared to anyone. While the discussion is about who will mark him, and how, the answer actually is not to mark him but mark the spaces he will look to exploit.

Every world-class forward likes to operate in the space between defence and midfield. United's back four really do have to concentrate and communicate with those in front of them – probably Michael Carrick and Phil Jones – in the Bernabeu. They cannot let Ronaldo get the ball and turn them in this area and start running at Rio Ferdinand and Nemanja Vidic. They will need protection.

2. Have De Gea at his best

David de Gea has had a good run in the team of late and will be at home in Spain. If United are to go through, then the keeper will have to perform very well in both games. Madrid won't bombard him with crosses and set-pieces like some teams do in the Premier League, but he'll have to be at his shot-stopping best to keep Real out. Most professional players can look back and pick out a game that was a turning point in his career. This just might be that moment for De Gea.

3. Get Rooney around Alonso

Xabi Alonso makes Madrid tick, just as he did at Liverpool. He'll receive the ball from Sergio Ramos and look to pass to Madrid's three attacking midfield players, Ronaldo, Mesut Özil and Angel di Maria, in the same way he used to thread the ball through to Steven Gerrard and Fernando Torres. It would be ideal for Wayne Rooney to play just behind Robin van Persie and try and disrupt Alonso's game. Not only can he put pressure on Alonso by getting his head down, he can also break off him arriving into the box late.

4. Use Carrick wisely

Michael Carrick has had a brilliant season so far for United and has taken on the responsibility of United's main midfield man. His use of the ball has been exceptional, but this game is a real test for him. He has to be brave and want the ball in all areas. Madrid will likely have the majority of possession, but when United have the ball they need to keep it, to allow the team time to move up the pitch and regain their shape. Carrick will be key to turning of defence into attack.

5. Get distances right

United have to get their distances right. That means they cannot allow Madrid too much space to operate between the lines – the space between defence and midfield and behind United's back four. Chelsea were tactically superb last year against Barcelona. They simple denied Lionel Messi and co any space or freedom to play in. They marked spaces not players which was key to their success. United will have to be at their most disciplined of the season to be in with a shout.